Active Center Of Glucose Oxidase Research Articles

Development of Nanocomposite Materials Based on Conductive Polymers for Using in Glucose Biosensor.

Electropolymerized neutral red, thionine, and aniline were used as part of hybrid nanocomposite conductive polymers, to create an amperometric reagent-less biosensor for glucose determination. The structure of the obtained polymers was studied using infrared (IR) spectroscopy and scanning electron microscopy. Electrochemical characteristics were studied by cyclic voltammetry and impedance spectroscopy. It was shown that, from the point of view of both the rate of electron transfer to the electrode, and the rate of interaction with the active center of glucose oxidase (GOx), the most promising is a new nanocomposite based on poly(neutral red) (pNR) and thermally expanded graphite (TEG). The sensor based on the created nanocomposite material is characterized by a sensitivity of 1000 ± 200 nA × dm3/mmol; the lower limit of the determined glucose concentrations is 0.006 mmol/L. The glucose biosensor based on this nanocomposite was characterized by a high correlation (R2 = 0.9828) with the results of determining the glucose content in human blood using the standard method. Statistical analysis did not reveal any deviations of the results obtained using this biosensor and the reference method. Therefore, the developed biosensor can be used as an alternative to the standard analysis method and as a prototype for creating sensitive and accurate glucometers, as well as biosensors to assess other metabolites.

Green rust (GR) and glucose oxidase (GOX) based Fenton-like reaction: Capacity of sustainable release, promoted conversion of glucose through GOX-iron and pH self-adjustment

The Fenton reaction is regarded as highly efficient for the degradation of organic contaminants. However, the traditional Fenton reaction is still flawed in a narrow pH working range and low utilization efficiency of the reagents. Based on two striking features, a sustained release of H2O2 in-situ under the catalysis of glucose oxidase (GOX) and the rapid electron donation & transferability from green rust (GR), an adaptable biological Fenton-like system (GGGMFs) was established. The coupling roles of glucose, GOX and GR in the degradation of 3,4-dimethylaniline (3,4-DMA) and the types of reactive species were deduced by electron spin resonance (ESR), etc.. Results demonstrated that the suitable pH range of the system was optimized from acidic to circumneutral, which was favorable for practical application, owing to the heterogeneous formation of GR and the pH self-adjustable capacity of GOX-Glucose. Meanwhile, hydroxyl radical (·OH), superoxide radical (·O2−) and Fe (IV) were identified to be the main oxidizing reactive species. Taking different selectivity of the reactive species to certain pollutant functional groups into consideration, the degradation pathways of 3,4-DMA were proposed. Moreover, it was shown that GR not only acted as the activating substance of the Fenton-like reaction, but also enhanced the activity of GOX, resulting in the promotion of glucose conversion in GGGMFs. This study shed light on the enhancement mechanism consisting of two aspects: (i) the elimination of product inhibition (ii) the formation of a 2Fe(III)-FAD complex with FAD, the active center of GOX, which prompted the electronic transfer in the enzyme catalytic reaction.

Electronic state calculation of the active center of Glucose Oxidase by QCLO method

Electronic state calculation of the active center of Glucose Oxidase by QCLO method

Electrochemical co-reduction synthesis of graphene/nano-gold composites and its application to electrochemical glucose biosensor

A simple, green and controllable approach was employed for electrochemical synthesize of the graphene/nano-Au composites. The process was that graphene oxide and HAuCl4 was electrochemically co-reduced onto the glassy carbon electrode (GCE) by cyclic voltammetry in one step. The obtained graphene/nano-Au/GCE exhibited high electrocatalytic activity toward H2O2, which resulted in a remarkable decrease in the overpotential of H2O2 electrochemical oxidation compared with bare GCE. Such electrocatalytic behavior of the graphene/nano-Au/GCE permitted effective low-potential amperometric biosensing of glucose via the incorporation of glucose oxidase (GOD) with graphene/nano-Au. An obvious advantage of this enzyme electrode (graphene/nano-Au/GOD/GCE) was that the graphene/nano-Au nanocomposites provided a favorable microenvironment for GOD and facilitated the electron transfer between the active center of GOD and electrode. The immobilized GOD showed a direct, reversible redox reaction. Furthermore, the graphene/nano-Au/GOD/GCE was used as a glucose biosensor, displaying a low detection limit of 17μM (S/N=3), a high sensitivity of 56.93μAmM−1cm−2, acceptable reproducibility, very good stability, selectivity and anti-interference ability.

Direct electrochemistry of glucose oxidase immobilized on nanostructured gold thin films and its application to bioelectrochemical glucose sensor

Glucose oxidase (GOx) was stably immobilized via a simple physical adsorption method onto the nanostructured Au thin films fabricated by using electrodeposition and galvanic replacement technology, which provides a facile method to prepare morphology-controllable Au films and also facilitates the preparation and application of enzyme modified electrodes. An obvious advantage of the as-prepared enzyme electrode (denoted as GOx/Au/GCE) is that the nano-Au films provide a favorable microenvironment for GOx and facilitate the electron transfer between the active center of GOx and electrodes. Cyclic voltammetry (CV) results indicate that the immobilized GOx displayed a direct, reversible and surface-confined redox reaction in the phosphate buffer solution. Furthermore, the enzyme modified electrode was used as a glucose bioelectrochemical sensor, exhibiting a linear relationship in the concentration ranges of 2.5–32.5μmolL−1 and 60–130μmolL−1 with a detection limit of 0.32μmolL−1 (S/N=3) at an applied potential of −0.55V. Due to the excellent stability, sensitivity and anti-interference ability, the Au thin films are hopeful in the construction of glucose biosensors.

Direct electron transfer and electrocatalysis of glucose oxidase immobilized on glassy carbon electrode modified with Nafion and mesoporous carbon FDU-15

In this paper, it was found that glucose oxidase (GOD) has been stably immobilized on glassy carbon electrode modified with mesoporous carbon FDU-15 (MC-FDU-15) and Nafion by simple technique. The sorption behavior of GOD immobilized on MC-FDU-15 matrix was characterized by transmission electron microscopy (TEM), ultraviolet–visible (UV–vis), FTIR, respectively, which demonstrated that MC-FDU-15 could facilitate the electron exchange between the active center of GOD and electrode. The direct electrochemistry and electrocatalysis behavior of GOD on the modified electrode were characterized by cyclic voltammogram (CV) which indicated that GOD immobilized on Nafion and MC-FDU-15 matrices display direct, reversible and surface-controlled redox reaction with an enhanced electron transfer rate constant of 4.095 s −1 in 0.1 M phosphate buffer solution (PBS) (pH 7.12). Furthermore, it was also discovered that, in the presence of O 2, GOD immobilized on Nafion and MC-FDU-15 matrices could produce a linear response to glucose. Thus, Nafion/GOD-MC-FDU-15/GC electrode is hopeful to be used in glucose biosensor. In addition, GOD immobilized on MC-FDU-15 and Nafion matrices possesses an excellent bioelectrocatalytic activity for the reduction of O 2. So, the Nafion/GOD-MC-FDU-15/GC electrode can be utilized as the cathode in biofuel cell.

Alternative route to reconstitute an electrical contact of enzyme on a single-walled carbon nanotube–ferrocene hybrid

Ferrocene was immobilized on the surfaces of single-walled carbon nanotube (SWCNT) bundles, and the ferrocene/SWCNT hybrid shows a high stability not only in water but also in an organic solvent. Furthermore, the nanohybrid exhibits greatly improved electron-transfer behavior and provides more electrochemical active sites. This study presents an alternative route to reconstitute an electrical contact through a single-walled carbon nanotube–ferrocene hybrid between the active center of glucose oxidase and the electrode. The fabricated glucose biosensor shows a fast rate and a high sensitivity.

Mediated Bioelectrocatalytic Oxidation of Glucose on a Glucose Oxidase-Containing Composite

A composite material, which includes glucose oxidase (GOD), finely divided colloidal graphite, ferrocene, and Nafion, is developed and investigated. Kinetic parameters of redox conversions of GOD and flavin adenine dinucleotide, which is present in the active center of GOD, indicate that GOD in the composite retains molecular integrity and enzymic activity. Ferrocene in the composite undergoes reversible oxidation and is reduced on the electrode. Bioelectrocatalytic oxidation of glucose on the composite occurs via a mediator path, and the half-wave potential of a polarization curve recorded on the electrode in the presence of glucose coincides with the redox potential of ferrocene, which is equal to 0.32 V (Ag/AgCl). Effect of the ferrocene amount in the composite and the glucose concentration in the bulk solution on the glucose oxidation is studied. The results are used to optimize the composite's composition to ensure a stable operation of the enzyme electrode and effective glucose oxidation.

Electrochemical analysis of the coordination sphere of ruthenium(ii) as electron transfer mediator in glucose oxidase catalysis in aqueous solutions

The redox potentials of the cis-[Ru(LL)2XY]n+ complexes (LL = 2,2"-bipyridyl (bpy), 1,10-phenanthroline (phen), and 4,4"-dimethyl-2,2"-bipyridyl (Me2bpy); X, Y = Cl–, Br–, CO32–, NO2–, SCN–, N3–, H2O, and DMSO) in aqueous buffer solutions were measured and analyzed in the framework of the Lever theory on the additivity of contributions of ligands (EL) to the apparent redox potential of the complex (Eo"). The complexes manifest the properties of reversible or quasireversible redox systems, whose formal redox potentials lie in the 0.2—0.5 V range. The complexes are efficient electron transfer mediators between the active center of glucose oxidase (GO) from Aspergillus niger and an electrode.

Electron transfer between an electrochemically deposited glucose oxidase/Cu[II] complex and an electrode

Glucose oxidase (GOD) complexed with Cu[II] was deposited on the electrode surface with retention of enzyme activity by an electrochemical reduction of Cu[II]. The deposited GOD showed an apparently reversible electron transfer to an electrode through the coordinated Cu. The GOD/Cu electrode responded to glucose in anodic current due to an electrochemical oxidation of enzymatically generated FADH. In conclusion, the electron transfer was mediated by bound Cu which was situated at an active center of GOD. The GOD/Cu system provided an “atomic interface” to perform a smooth electron transfer between a flavoenzyme and an electrode.

Observation of direct electron transfer from the active center of glucose oxidase to a graphite electrode achieved through the use of mild immobilization

An immobilization method based on the use of aminophenylboronic acid enhanced the rate of electron transfer between glucose oxidase and a graphite electrode. Under anaerobic conditions, a group of 21 electrodes responded to a 10 mM change in glucose concentration with an average change of current of 0.5 ± 0.1 μA. Experimental evidence ruled out the possibility of (natural or artificial) mediated electron transfer or a mechanism based on orientation of the enzyme. A mechanism for electron transfer promotion based on the prevention by aminophenylboronic acid of the removal of the FAD from enzymes well situated and/or oriented to transfer electrons directly is postulated. To support this mechanism, experimental evidence was found confirming the removal of FAD from the enzyme by the graphite electrode and a protective role against it of aminophenylboronic acid.

413 — Biocatalytic oxidation of glucose on the conductive charge transfer complexes

Glucose oxidase entrapped in the layer near the electrode surface of conductive charge-transfer complexes or on glassy carbon electrodes modified by tetracyano-quinodimethane (or by its K-salt) catalyzes the electrochemical oxidation of glucose in the interval from −0.05 to 0.4 V ( vs. Ag⋎AgCl). When enzyme electrodes operate in a switched-off state the charge is accumulated in the complexes. The components of the complexes oxidize the active center of glucose oxidase. A scheme for electrocatalytic oxidation of glucose by mediators is proposed.

Biocatalytic oxidation of glucose on the conductive charge transfer complexes

Glucose oxidase entrapped in the layer near the electrode surface of conductive charge-transfer complexes or on glassy carbon electrodes modified by tetracyano-quinodimethane (or by its K-salt) catalyzes the electrochemical oxidation of glucose in the interval from −0.05 to 0.4 V ( vs. Ag|AgCl). When enzyme electrodes operate in a switched-off state the charge is accumulated in the complexes. The components of the complexes oxidize the active center of glucose oxidase. A scheme for electrocatalytic oxidation of glucose by mediators is proposed.